CPQ, also known as PGCP, is a carboxypeptidase and a member of peptidase family M28. CPQ is a secreted protein hydrolyzing the circulating peptides in the extracellular microenvironment [, ]. It has been shown to liberates I-thyroxine (T4) from thyroglobulin (Tg) []. PGCP has been associated with pulmonary hypertension [].